Self-repairing steel pipe concrete structure based on negative Poisson's ratio / FRP composite material constraint

Abstract

The invention discloses a self-repairing concrete-filled steel tube structure based on negative poisson ratio / FRP composite material constraint. The self-repairing concrete-filled steel tube structure comprises a core steel tube, a self-repairing constraint system and a pre-fastening system, the self-repairing restraint system comprises an inner FRP layer and an outer FRP layer which are coaxially arranged, and the inner FRP layer is tightly fixed to the outer surface of the core steel pipe. A plurality of annular base plates are arranged between the inner FRP layer and the outer FRP layer at intervals from bottom to top, and the base plates are matched with a gap between the inner FRP layer and the outer FRP layer; a negative poisson ratio material layer is arranged between any two adjacent base plates; the pre-fastening system is used for connecting all the base plates and the negative poisson ratio material layers into a whole; and a repair liquid release ball is arranged in the negative Poisson's ratio material layer close to the inner FRP layer. The defects that a traditional concrete-filled steel tube structure is poor in shock resistance and cannot be self-repaired after disasters are overcome, and the shock resistance toughness and the residual bearing capacity after disasters of the concrete-filled steel tube structure are remarkably improved.

Description

Technical Field

[0001] The invention relates to a steel tube concrete structure, in particular to a self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraints. Background Art

[0002] Steel tube concrete structures have been widely used in many civil engineering structures such as long-span arch bridges and bridge piers due to their good mechanical properties. This structure fills the steel tube with concrete, giving full play to the tensile properties of steel and the compressive properties of concrete. It has high strength and rigidity and can reliably bear various loads under normal use conditions.

[0003] However, in actual engineering, steel tube concrete structures face many severe challenges. Under the action of earthquakes, strong ground vibrations will cause the structure to vibrate and deform violently, which can easily lead to a decrease in the collaborative working performance between the steel tube and concrete, and even cause the overall destruction of the structure. Accidental impacts such as ship collisions and vehicle collisions can also cause serious damage to steel tube concrete structures, which may cause local dents in the steel tube and cracks in the concrete, thereby affecting the safety and normal use of the structure. Repairing damaged structures often requires a lot of manpower, material resources and time costs, and it is difficult for the structural performance after repair to be fully restored to its original state.

[0004] At present, how to improve the seismic ductility, impact resistance and post-disaster self-recovery of CFST structures has become one of the hot issues in the engineering field. Although traditional CFST structures can meet the needs of conventional engineering to a certain extent, their impact resistance is poor, and they are prone to irreversible damage after unexpected impacts, and they do not have the ability to self-repair after disasters. This makes it difficult for traditional CFST structures to ensure the safety and durability of the structure when facing extreme effects such as earthquakes and impacts. Summary of the invention

[0005] Purpose of the invention: The purpose of the invention is to provide a steel tube concrete structure with impact resistance and self-recovery ability.

[0006] Technical solution: A self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraints of the present invention includes a core steel tube, a self-repairing constraint system and a pre-tightening system; the self-repairing constraint system includes a coaxially arranged inner FRP layer and an outer FRP layer, wherein the inner FRP layer is tightly fixed to the outer surface of the core steel tube; a plurality of annular pads are arranged between the inner and outer FRP layers from bottom to top, and the pads are adapted to the gap between the inner and outer FRP layers; a negative Poisson's ratio material layer is arranged between any two adjacent pads; the pre-tightening system is used to connect all pads and negative Poisson's ratio material layers as a whole; a repair liquid release ball is arranged in the negative Poisson's ratio material layer near the inner FRP layer.

[0007] Furthermore, the repair liquid releasing ball has a shell filled with the repair liquid and compressed gas.

[0008] Furthermore, the negative Poisson's ratio material layer includes a plurality of negative Poisson's ratio material layer constituent units distributed in an array, the repair liquid releasing balls are placed in the negative Poisson's ratio material layer constituent units, and the wall surfaces of the negative Poisson's ratio material layer constituent units are provided with repair liquid releasing holes.

[0009] Furthermore, when the negative Poisson's ratio material layer is extruded and deformed, the repair liquid release ball ruptures, and the compressed gas squeezes the repair liquid out of the repair liquid release hole. At the same time, the inner FRP layer is damaged and torn, and the generated FRP fibers provide a medium for the attachment of the repair liquid.

[0010] Furthermore, the pre-tightening system includes a shape memory alloy reinforcement, and the pad is provided with a through hole for the shape memory alloy reinforcement to pass through; both ends of the shape memory alloy reinforcement are fixed by pads and anchor nuts.

[0011] Furthermore, after the shape memory alloy reinforcement is installed, an external power supply is used to connect the two ends of the shape memory alloy reinforcement and input a certain amount of current. The shape memory alloy reinforcement is heated based on the principle of resistive heating, and the shape memory effect is used to apply the preload.

[0012] Shape memory alloy reinforcements can restore preload after the structure is deformed under stress, ensuring the integrity and stability of the structure and further improving the performance and reliability of the structure.

[0013] Furthermore, the negative Poisson's ratio material layer is made by 3D printing.

[0014] Furthermore, the inner FRP layer is bonded to the outer surface of the core steel pipe by structural adhesive.

[0015] Furthermore, the structural adhesive includes epoxy resin.

[0016] Furthermore, the spacings between adjacent pads are equal.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0018] (1) Significantly improve the impact resistance of the steel tube concrete structure: through the special mechanical properties of the negative Poisson's ratio material layer, it effectively absorbs and disperses the impact energy, reducing the degree of damage to the structure under impact;

[0019] (2) Enhanced seismic toughness of the steel tube concrete structure: The inner FRP layer, negative Poisson's ratio material layer and outer FRP layer work together to improve the deformation capacity and energy dissipation capacity of the structure under earthquake action, reducing the risk of structural collapse and damage;

[0020] (3) It has post-disaster self-repair function: when the structure is damaged, the repair liquid release ball ruptures to release the repair liquid. Under the action of compressed gas, the repair liquid is squeezed out through the repair liquid release hole to repair the damaged part, thereby improving the post-disaster residual bearing capacity of the structure and reducing the repair cost and time;

[0021] In summary, the present invention comprehensively utilizes the restraining performance of FRP materials on the core steel tube concrete, the impact resistance of the negative Poisson's ratio material layer and the self-repairing performance of the repair fluid after release, so as to improve the seismic ductility, impact resistance and self-recovery ability of the post-disaster mechanical properties of the steel tube concrete structure, make up for the defects of the traditional structure, significantly enhance the seismic toughness and post-disaster residual bearing capacity of the steel tube concrete structure, so as to ensure the safety and durability of the structure under extreme conditions and reduce the losses caused by structural damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint provided by an embodiment of the present invention;

[0023] Figure 2 yes Figure 1 A partial cross-sectional view of

[0024] Figure 3 yes Figure 2 A top view of

[0025] Figure 4 yes Figure 1 A full cross-sectional view of

[0026] Figure 5 is a full cross-sectional view of a negative Poisson's ratio material layer component unit and a repair liquid release ball in an embodiment of the present invention;

[0027] Figure 6 is a schematic diagram of a pad in an embodiment of the present invention;

[0028] Figure 7 Schematic diagram of a pre-tightening system in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] Attached Figures 1 to 7 The reference numerals in the figures are as follows:

[0031] 1. Core steel pipe; 2. Self-repairing restraint system; 21. Inner FRP layer; 22. Negative Poisson's ratio material layer; 221. Backing plate; 2211. Through hole; 222. Repair fluid release ball; 2221. Outer shell; 2222. Repair fluid; 2223. Compressed gas; 223. Negative Poisson's ratio material layer component unit; 224. Repair fluid release hole; 23. Outer FRP layer; 3. Pre-tightening system; 31. Shape memory alloy reinforcement; 32. Spacer; 33. Anchor nut.

[0032] like Figures 1 to 7 As shown, an embodiment of the present invention provides a self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraints, including a core steel tube 1, a self-repairing constraint system 2 and a pre-fastening system 3.

[0033] The self-repairing restraint system 2 includes a coaxially arranged inner FRP layer 21 and an outer FRP layer 23. The inner FRP layer 21 is tightly bonded to the outer surface of the core steel pipe 1 by structural adhesive (such as epoxy resin, etc.) to provide a preliminary restraint effect. A plurality of annular pads 221 are arranged from bottom to top between the inner and outer FRP layers. The pads 221 are adapted to the gap between the inner and outer FRP layers, and the spacing between adjacent pads 221 is equal.

[0034] A negative Poisson's ratio material layer 22 is provided between any two adjacent pads 221. With the special mechanical properties of the negative Poisson's ratio material, the impact resistance and deformation capacity of the structure are improved. The negative Poisson's ratio material layer 22 is made by 3D printing. A repair liquid release ball 222 is provided in the negative Poisson's ratio material layer 22 near the inner FRP layer 21. Specifically,

[0035] The negative Poisson's ratio material layer 22 includes a plurality of negative Poisson's ratio material layer component units 223 distributed in an array, the repair liquid release balls 222 are placed in the negative Poisson's ratio material layer component units 223 , and the wall surface of the negative Poisson's ratio material layer component units 223 is provided with repair liquid release holes 224 .

[0036] The repair liquid releasing ball 222 has a shell 2221 , and the shell 2221 is filled with a repair liquid 2222 and a compressed gas 2223 .

[0037] The pre-fastening system 3 is used to connect all the pads 221 and the negative Poisson's ratio material layer 22 as a whole. Specifically,

[0038] The pre-tightening system 3 includes a shape memory alloy rib 31. The pad 221 is provided with a through hole 2211 for the shape memory alloy rib 31 to pass through. Both ends of the shape memory alloy rib 31 are fixed by a pad 32 and an anchor nut 33. After the structure is deformed by force, the structural pre-tightening force can be restored by using the characteristics of the shape memory alloy.

[0039] When the structure is damaged, the negative Poisson's ratio material layer component unit 223 is squeezed and deformed, the repair liquid release ball 222 ruptures, and the compressed gas 2223 squeezes the repair liquid 2222 out of the repair liquid release hole 224, realizing the self-repair function of the structure. When the core steel pipe 1 is crushed, cracked, etc., the inner FRP layer 21 may be damaged, torn, etc. at the same time, and the FRP fibers produced thereby provide a medium for the attachment of the repair liquid 2222.

[0040] The method for manufacturing the self-repairing steel tube concrete structure described in the embodiment of the present invention is as follows.

[0041] The outer surface of the core steel pipe 1 is derusted and cleaned, and the inner FRP layer 21 is tightly adhered to the outer surface of the core steel pipe 1 using structural adhesive such as epoxy resin.

[0042] The outer diameter of the composite structure composed of the core steel pipe 1 and the inner FRP layer 21 is measured, and a negative Poisson's ratio material layer 22 of a suitable size is manufactured based on 3D printing technology, and a backing plate 221 of a corresponding size is simultaneously manufactured.

[0043] The first pad 221 is inserted into the composite structure composed of the core steel pipe 1 and the inner FRP layer 21 as the bottom plate, and then the negative Poisson's ratio material layer 22 is inserted and the repair liquid release ball 222 is placed in the negative Poisson's ratio material layer component unit 223 close to the inner FRP layer 21. Next, the second pad 221, the second negative Poisson's ratio material layer 22, and the repair liquid release ball 222 are inserted. Repeat the above operation until the last pad 221 (i.e., the top plate) is placed.

[0044] The shape memory alloy rib 31 is passed through the through hole 2211 on the surface of the pad 221, and is anchored with the pad 32 and the anchor nut 33. An external power source is used to connect the two ends of the shape memory alloy rib 31 and input a certain amount of current, and the shape memory alloy rib 31 is heated based on the principle of resistance heating, and the preload force is applied by using its shape memory effect.

[0045] Finally, concrete is poured into the core steel pipe 1 to complete the production.

Claims

1. A self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint, characterized in that: The invention comprises a core steel pipe (1), a self-repairing restraint system (2) and a pre-tightening system (3); the self-repairing restraint system (2) comprises an inner FRP layer (21) and an outer FRP layer (23) which are coaxially arranged, wherein the inner FRP layer (21) is tightly fixed to the outer surface of the core steel pipe (1); a plurality of annular pads (221) are arranged between the inner and outer FRP layers from bottom to top, and the pads (221) are adapted to the gap between the inner and outer FRP layers; a negative Poisson's ratio material layer (22) is arranged between any two adjacent pads (221); the pre-tightening system (3) is used to connect all the pads (221) and the negative Poisson's ratio material layers (22) as a whole; and a repair liquid release ball (222) is arranged in the negative Poisson's ratio material layer (22) at a position close to the inner FRP layer (21).

2. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 1 is characterized in that: The repair liquid release ball (222) has a shell (2221), and the shell (2221) is filled with repair liquid (2222) and compressed gas (2223).

3. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 2 is characterized in that: The negative Poisson's ratio material layer (22) comprises a plurality of negative Poisson's ratio material layer component units (223) distributed in an array, the repair liquid release balls (222) are placed in the negative Poisson's ratio material layer component units (223), and the wall surfaces of the negative Poisson's ratio material layer component units (223) are provided with repair liquid release holes (224).

4. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 3 is characterized in that: When the negative Poisson's ratio material layer (22) is squeezed and deformed, the repair liquid release ball (222) ruptures, and the compressed gas (2223) squeezes the repair liquid (2222) out of the repair liquid release hole (224). At the same time, the inner FRP layer (21) is damaged and torn, and the generated FRP fibers provide a medium for the adhesion of the repair liquid (2222).

5. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 1, characterized in that: The pre-tightening system (3) comprises a shape memory alloy reinforcing bar (31); the backing plate (221) is provided with a through hole (2211) for the shape memory alloy reinforcing bar (31) to pass through; and both ends of the shape memory alloy reinforcing bar (31) are fixed by means of a cushion block (32) and an anchor nut (33).

6. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 5, characterized in that: After the shape memory alloy reinforcement (31) is installed, an external power source is used to connect the two ends of the shape memory alloy reinforcement (31) and input a current of a certain magnitude, so that the shape memory alloy reinforcement (31) is heated based on the principle of resistance heating, and the preload force is applied by utilizing its shape memory effect.

7. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 1, characterized in that: The negative Poisson's ratio material layer (22) is manufactured by 3D printing.

8. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 1, characterized in that: The inner FRP layer (21) is bonded to the outer surface of the core steel pipe (1) by means of structural adhesive.

9. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 8, characterized in that: The structural adhesive includes epoxy resin.

10. The self-repairing steel tube concrete structure based on negative Poisson's ratio / FRP composite material constraint according to claim 1, characterized in that: The spacing between adjacent pads (221) is equal.

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